Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Pig >> mail # user >> Join Question

Copy link to this message
Re: Join Question
I think there's probably some convoluted way to do this. First thing you'll
have to do is flatten your data.

data1 = A, B
X, X1
X, X2
Y, Y1
Y, Y2
Y, Y3

Then do a  join by "B" onto you second dataset. This should produce the

data2 = data1::A, data1::B, data2::A, data2::B, data2::C (I'm assuming data
set has exactly 4 columns).
X, X1, X1, 4, 5, 6
X, X2, X2, 3, 7, 3

Now do a group by data1::A to get
{X, {(X, X1, X1, 4, 5, 6), (X, X2, X2, 3, 7, 3), ...}}
{Y, {(Y, Y1, Y1, ...), (Y, Y2, Y2, ...), ...}}

This is as far as I got, I'm not sure if there's a built-in UDF to
transform that into what you're looking for. I thought maybe BagToTuple,
but it will return a single tuple with all elements of all tuples in the
bag. If the above data format supports your use cases, you're done. If not,
you can write a UDF to transform it into the required format.
On Wed, Sep 4, 2013 at 4:39 PM, F. Jerrell Schivers

> Howdy folks,
> Let's say I have a set of data that looks like this:
> X, (X1, X2)
> Y, (Y1, Y2, Y3)
> So there could be an unknown number of members of each tuple per row.
> I also have a second set of data that looks like this:
> X1, 4, 5, 6
> X2, 3, 7, 3
> I'd like to join these such that I get:
> X, (X1, 4, 5, 6), (X2, 3, 7, 3)
> Y, (Y1, etc), (Y2, etc), (Y3, etc)
> Is this possible with Pig?
> Thanks,
> Jerrell